46 BBC SCIENCE FOCUS MAGAZINE COLLECTIONDIETe’re becoming more
obese, as a society.
Is this because
some of us are
addicted to certain
foods? One study,
at Connecticut College in 2013, suggested
that Oreos were “as addictive as cocaine”.
Certainly, some people who are overweight
exhibit behaviours associated with addiction,
such as an inability to avoid particular foods
and a tendency to over-eat at times of stress. But
this is not true of all overweight individuals.
So does ‘food addiction’ actually exist?
To answer that, we first need to understand
what addiction is. The Diagnostic and
Statistical Manual
of Mental Disorders
cites developing a
tolerance, becoming
dependent and having
withdrawal symptoms.
The latest version,
DSM-5, added: “craving
or a st rong desi re or u r ge
to use a substance”.
Addiction affects
areas of the brain that
are linked to pleasure,
reward and decision-
making. It also affects
neurotransmitters, the chemical signals used
for communication between brain cells and
brain regions. Over time, memory of previous
exposures to rewards (such as food, sex,
alcohol or drugs) leads to a biological response,
such as cravings.
The best tool that researchers have for
applying all this to food is the Yale Food
Addiction Scale (YFAS). This 25-point
questionnaire was developed in 2009 by
Dr Ashley Gearhardt, an assistant professor
of clinical psychology at the University of
Michigan. She believes addictive processes
do play a role in eating-related problems. “My
research asks, how can we identify that group
of people who are most likely to be showing
an addictive response to food? The Yale Food
Addiction Scale does not use bodyweight to
identify people who could be addictive eaters;instead, it uses the same criteria used for any
addiction. This gives us a starting point, so
we can look at whether there are behavioural,
cognitive or biological markers in this group.”
In one experiment, Dr Gearhardt showed
people pictures of ‘treats’ such as chocolate
milkshakes, then gave them the real thing. She
found that people who have more ‘addictive-
like’ eating behaviour have more activity in
brain regions linked to reward and desire when
exposed to ‘addictive cues’ – the pictures of
treats – than when they saw other images. They
also have less of an inhibitory response in the
brain once they’ve drunk the milkshake than
after consuming other non-addictive foods.
“This indicates that this group of people is
very reactive to cues in
the environment that
suggest these foods
are available,” says
Dr Gearhardt. “When
they start consuming,
the circuitry in the
brain that usually
allows people to apply
the brakes and stop
eating may not be
working as well.”
This same pattern
is also seen in people
with ‘conventional’
addictions. According to Dr Gearhardt, this
further strengthens the case for food addiction.
In another study, Dr Gearhardt’s team recruited
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which foods they were thinking of while
reading particular statements. The usual
suspects were at the top of the list: ice cream,
chocolate, biscuits, sweets. According to Dr
Gearhardt, these are foods our brains have not
really evolved to handle yet.SUGAR HIT
Modern diets contain far more processed, sugar-
heavy food than those of previous generations,
and it’s showing on our waistlines. NHS stats
show the proportion of obese adults rose
between 1993 and 2013, from 58 to 67 per cent
in men and from 49 to 57 per cent in women.
This is set to rise even further, predicts the“The circuitry in the
brain that usually
allows people to apply
the brakes and stop
eating may not be
working as well”
W
RIGHT: People who
completed the Yale
Food Addiction Scale
identified pizza as
the most ‘addictive’
food of all
BELOW: Modern diets
contain more sugar
than those enjoyed by
previous generations
BELOW RIGHT: Sugar
boosts dopamine
production and
triggers the brain’s
reward pathwaysDIET46 BBC SCIENCE FOCUS MAGAZINE COLLECTIONISTOCK X2, SCIENCE PHOTO LIBRARY